1. Field of the Invention
The invention relates to a fast response current source. Particularly, the invention relates to a fast response current source capable of dynamically adjusting an output current according to a load demand.
2. Description of Related Art
In a conventional voltage regulator, a feedback circuit is generally used to lock an output voltage to be generated, and a regulation capacitor is disposed at an output terminal of the voltage regulator to assist voltage regulation capability of the voltage regulator. Configuration of the regulation capacitor is mainly to convert pre-stored charges into a driving current for providing to a load when a demand current of the load driven by the voltage regulator is sharply varied, so as to maintain stability of the voltage output from the output terminal of the voltage regulator. In other words, to ensure that the voltage regulator endures a large variation of the demand current of the load, the regulation capacitor of a large size has to be used. Configuration of the large size regulation capacitor increases the cost of the voltage regulator and decreases a response speed of the voltage regulator.
Certainly, in the conventional voltage regulator, a design without using the regulation capacitor is also provided, and such type of the voltage regulator requires a complicated detecting circuit to detect a dynamic variation of the demand current of the load through the output terminal of the voltage regulator, and dynamically adjust the driving current generated by the voltage regulator according to the detected dynamic variation of the demand current of the load. Since such voltage regulator requires the complicated current detecting circuit, the circuit cost is increased and additional current consumption of the current detecting circuit is required.